1. Field of the Invention
The present invention relates to a vehicle switch used for turning a stop lamp on/off for example when a brake pedal of a motor vehicle is operated in particular.
2. Background Art
Recently, a pressure type switch is used as a vehicle switch for transmitting the operation of a brake pedal to a controller. When the operation of the brake pedal depressed is transmitted, the controller serves to turn on a stop lamp. With the brake pedal released, the controller serves to turn off the stop lamp.
Such a conventional vehicle switch is described with reference to FIG. 7 and FIG. 8. FIG. 7 is a sectional view of conventional vehicle switch 11. In the figure, casing 12 includes case 1 and cover 10. Case 1 is made of insulating resin and opens upward in the figure. Cover 10 is made of insulating resin and disposed so as to cover the opening of case 1. Tube 10A is disposed at the upper part of cover 10. Actuator 2 and spring 9 are disposed in casing 12. Actuator 2 is installed in such manner as to be vertically movable in tube 10A. In the figure, coil spring 9 is disposed between a hollow portion of actuator 2 and bottom 1A of case 1. Due to restoring force of spring 9, actuator 2 is pressed against cover 10. End 2A of actuator 2 is protruded upward from tube 10A.
Casing 12 is internally provided with magnet 3 and detector 6 in such manner as to be opposed to each other. Magnet 3 is disposed on the lower side surface of actuator 2. Detector 6 is formed of Hall Element and the like and disposed on wiring board 5. On wiring board 5 are disposed switching part 7 such as transistor or the like, and controller 8 formed of FET and a plurality of fixed resistors, etc. As to a plurality of terminals 4 made of conductive metal, one end thereof is connected to wiring board 5, and the other end is protruded outside the casing 12 from hole 1B of bottom 1A. Wiring patterns are provided on the right and left surfaces of wiring board 5. Terminal 4, detector 6, switching part 7, and controller 8 are electrically connected via the wiring patterns. These electronic parts are electrically connected by using solder or the like.
FIG. 8 shows a state of above-mentioned vehicle switch 11 mounted in a motor vehicle. Vehicle switch 11 and arm 13A are fitted in holding member 20. Arm 13A and holding member 20 are connected to each other on fulcrum 20A of arm 13A. Brake pedal 13 is attached to the tip of arm 13A. Arm 13A and vehicle switch 11 are in contact with each other via the end 2A of actuator 2. Connector 14 is connected to vehicle switch 11. Terminal 4 shown in FIG. 7 connects to a stop lamp and ignition switch of the motor vehicle, battery, electronic circuits of the motor vehicle, etc. via lead wires 14A of connector 14.
In FIG. 8, the state of arm 13A and brake pedal 13 shown by solid line indicates a state obtained when brake pedal 13 is not depressed. The state of arm 13A and brake pedal 13 shown by broken line indicates a state obtained when brake pedal 13 is depressed.
In the case, vehicle switch 11 shown in FIG. 7 changes as described in the following when brake pedal 13 is depressed. When brake pedal 13 is not depressed, the pressing force is applied downward in FIG. 7 to the end 2A of actuator 2. In other words, actuator 2 is in a state of being pressed downward. Magnet 3 disposed on the side surface of actuator 2 moves downward along with actuator 2. When brake pedal 13 is depressed, magnet 3 confronted detector 6, and when brake pedal 13 is not depressed, magnet 3 is positioned far away from detector 6. Consequently, the magnetism of magnet 3 detected by detector 6 becomes very weak.
Controller 8 operates as follows in accordance with the intensity of magnetism detected by detector 6.
When the magnetism detected exceeds the specified value, controller 8 detects that vehicle switch 11 is turned on. As a result, controller 8 turns on switching part 7 and turns on the stop lamp. When the magnetism detected is less than the specified value, controller 8 detects that vehicle switch 11 is turned off. As a result, controller 8 turns off the switching part 7 and turns off the stop lamp.
As described above, with actuator 2 depressed downward, the magnetism detected by detector 6 is very weak, that is, the magnetism is less than the specified value. Accordingly, controller 8 detects that vehicle switch 11 is turned off, then it turns off the switching part 7 and turns off the stop lamp.
With brake pedal 13 is depressed, the inside of vehicle switch 11 shown in FIG. 7 becomes as described in the following. When brake pedal 13 is depressed, arm 13A moves apart from the end 2A of actuator 2. As a result, the pressing force applied to actuator 2 by means of arm 13A is released, and then, due to the restoring force of spring 9, actuator 2 is moved upward. The condition is shown in FIG. 7. At the time, magnet 3 disposed on the side surface of actuator 2 moves upward along with actuator 2. As a result, magnet 3 and detector 6 become opposed to each other, intensifying the magnetism of magnet 3 detected by detector 6. In other words, the magnetism detected by detector 6 becomes higher than the specified value, and controller 8 detects that vehicle switch 11 is turned on. And controller 8 turns on switching part 7 and turns on the stop lamp.
That is, conventional vehicle switch 11 operates as follows. Actuator 2 vertically moves in tube 10A in accordance with the operation of brake pedal 13. Magnet 3 disposed on the side surface of actuator 2 moves along with actuator 2. The magnetism detected by detector 6 varies in accordance with the movement of magnet 3. When the magnetism detected by detector 6 is higher than the specified value, controller 8 detects that vehicle switch 11 is turned on. When the magnetism detected by detector 6 is less than the specified value, controller 8 detects that vehicle switch 11 is turned off. In accordance with the detection result of controller 8, controller 8 turns on/off the switching part 7, and turns on/off the stop lamp. Accuracy of control for turning on/off the stop lamp depends upon accuracy of positional relations between magnet 3 and detector 6.
In the assembly process of vehicle switch 11, if the position of each part is deviated, there arise positional deviation between magnet 3 and detector 6. As a result, it gives rise to the occurrence of variation or error in detection accuracy of the movement of actuator 2 with respect to the detection by magnet 3 and detector 6. Specifically, the assembly process includes a step of mounting detector 6 on wiring board 5, a step of fixing wiring board 5 to case 1, a step of fitting magnet 3 to actuator 2, or a step of installing actuator 2 in casing 12.
As prior art, for example, Unexamined Japanese Patent Publication No. 2006-92777 is known.
Actuator 2 on which magnet 3 is fixed and wiring board 5 on which detector 6 is mounted are different parts. Since these parts are different from each other in material and manufacturing method, their allowable values are different with respect to variation in shape and size or positional deviation in assembly of each part. Accordingly, when switch 11 is assembled by using these parts, positional deviation may be sometimes generated between magnet 3 and detector 6. As a result, there arises variation or error in the accuracy of detecting the position of magnet 3 by using magnet 3 and detector 6.